Incandescent electric lamp.



A. A. WILKINS. I INOANDESOBNT ELECTRIC LAMP. APPLICATION rum) anrr. 1a, 1900.

978,094. Patented Dec. 6, 1910.

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To all whom may co'rwer'n: A

UNITED STATES PATENT OFFICE.

ALBERT WILKINS, OF MIDDLETON, MASSACHUSETTS, ASSIG-NOR 0F ONE-HALF TO FREDERICK B. GAMPBELL AND CHARLES E. CAMPBELL, 0F LYNN, MASSACHUSETTS.

nrcannnscnn'r nnno'rnrc LAMP.

Be it knownthat-I, ALBERT A. WILKINS, a citizen. of the United States, residing at Middleton, in the-county of Essex-and State of Massachusetts, have invented certain new and useful Improvements in Incandescent Electric Lamps; and I do hereby declare the following tobeafull, clear, and exact description of} the. invention, such as will enable others skilled inthe art to which it appertains-tomake-and usethe same.

v The invention relates to incandescent electric 1am s. I

The object of the present invention is to produce an incandescent lamp having the advantages of the tungsten lamp without filament its delicacy and at the same time having the strength and durability of the carbon With the aibove object. in view the invention consists in' the incandescent lamp hereinafter described and particularly defined in the claims.

The accompanying drawing is a view in elevation of an incandescent amp embodying the invention.

As shown in the drawing the lamp comprises. a bulb 1 of glass provided with an external screw-threaded metal shell 2 and an internal depending stem'of glass 4 within which the leading-in wires 6 and 7 .are

sealed. All of the above elements are of well-known construction in the so-called Edison lamp. 1

The preferred embodiment of the-invention comprises a filament composed of alternate sections of carbon and tungsten. The two sections 9 and 10 are of carbon, such as is used in the ordinary carbon filament incandescent lamp, and are attached at their upper ends to the leading-in wires6 and 7 1 respectively. Thelower ends of the carbon {filament sections are cemented to the lower ends of'a tungsten filament' 12 by means .ot asuitable cement such as graphite and caramel paste. The tun ten filament is substantially U-shaped an sus ended in inverted position from its bend y a hook 14 secured in the glassstem 4.

The comparatlvely st1 act toteflectively support the lower ends Specification of Letters Patent. I Application filed September 13 1809. Serial No. 517,358.

. ported horizontally if carbon filaments Patented Dec. 6, 1910.

of the tungsten filament so that the only other support required is the book 14 at the bend in this filament. By this construction the glass support for the tungsten fila- 'ment is entirely eliminated. The carbon supports for the tungsten filamentfare sufficiently rigid and at the same time'sufi'iciently elastic to allow the lamp to be supor at any desired degree of inclination. T e lamp thus has the efficient light giving properties of the tungsten lamp with the durability and strengt of the carbon lam V a It is to be observed that various combinations of carbon and tungsten filamen s. may be made both as regards size and length of the portions, thus by increasing the length of the carbon filament and decreasing the length of the tungsten filament a com aratively cheap, low candle power, e cient lamp is produced. The carbon and the tungsten are bodies of difierent specific resistances and the invention contemplates in its broader aspects the use of a light giving element composed of sections of substances of difl'erent s ecific resistances. It is also to be observe that the co-eflicients of resistance of the two substances are the one positive and the other negative, and this is of value for reasons apparent to those skilled in the art.

The invention lends itself to the production of lam s of widely varying candle power, all 0 which have a resistance suitable'for use on ordinary incandescent circuits.

Having thus described the invention, what is claimed is 1. An incandescent electric lamp the light giving element of which is composed of alternate sections having positive and negative co-efiicients of resistance, substantia 1y as described.

2. An incandescent electric lamp the light giving element of which is composed of sections of carbon and tungsten arranged in.

series, substantially as described. a

. ALBERT A. WILKINS.

Witnesses:

Homes VAN Evnnnu, CHARLES E. CAMPBELL. 

